Exercise step



FIG. 1 is a top perspective view of an exercise step;

FIG. 2 is a bottom perspective view of the exercise step of FIG. 1;

FIG. 3 is a top plan view of FIG. 1;

FIG. 4 is a front elevational view of FIG. 1, the rear being a mirror image;

FIG. 5 is a right side elevational view of FIG. 3, the left side being a mirror image; and,

FIG. 6 is a bottom plan view of FIG. 3. 

The ornamental design for an exercise step, as shown and described. 